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windowsdelphilanguage-agnosticportable-executable

How do i determine exact PE image file size using its header(s)?

I need byte size, IMAGE_OPTIONAL_HEADER.SizeOfImage appears to be rounded up to (unsure) boundary and is greater than real file size.

Solution

  • IMAGE_OPTIONAL_HEADER.SizeOfImage is the size of the loaded executable/dll in virtual memory. It is not the same as the size on disk.

    You can calculate it with VirtualAddress + VirtualSize of the last section.

    IMAGE_OPTIONAL_HEADER.SizeOfImage is that value rounded up to the value of IMAGE_OPTIONAL_HEADER.SectionAlignment (usually the same as the page size).